Abstract
The difficulty of video display terminal users with bifocal lenses through a traditional workstation increases the complaints and risks for upper extremity cumulative trauma disorders. Furthermore, the regular and no lens users also have problems with traditionally designed workstations over prolonged periods of video display terminal use. A study was conducted on 14 subjects to investigate the effect of computer monitor location for video display terminal users with or without bifocals on subjective assessment and performance. The two monitor locations were 15° and 40° below horizontal eye level. The experimental task consisted of reading words from computer screens and typing them from the reverse side to the next column. Each experimental session lasted one hour. Males with bifocal lenses had less discomfort in the neck, shoulders, forearms, and wrists, less tiredness and eyestrain and higher performance with a 40° angle monitor than with a 15° angle monitor. A similar conclusion has been reached for females. Users with bifocal lenses had significantly higher neck discomfort and lower performance than nonbifocal users. The 40° angle monitor caused less neck discomfort than the 15° angle monitor did. Overall, females had less physical discomfort, less tiredness, and higher performance than males.
